CDKAL1 and gestational diabetes: Subsequently, an additional 51 studies were excluded for the following reasons: 1) 22 studies were not about CDKAL1 gene and GDM; 2) six articles concerned a non-human model of GDM; 3) 15 were not case–control or GWASs; and 4) eight studies did not focus on the topic of CDKAL1 rs7756992/rs7754840 and the risk of GDM.